Paper chase: firms including Cerner, iSoft and Emis are trying to help the NHS introduce electronic health records. Photograph: jiunlimited.com

If all goes well over the next few years, most NHS trusts and boards across the UK will be implementing electronic health records (EHRs) as a replacement for the medical records paper chase that has been in place at most health organisations for decades.

In England at least, however, bringing in EHRs will have been a tough job. The National Programme for IT (NPfIT) Care Records Service, which was meant to provide a centrally-bought system for many NHS trusts, has not delivered this for more than a handful, owing to continuing delays on several fronts.

Those suppliers already involved with the CRS could lose guaranteed customers, but would arguably be left in a strong position to compete, given the years of work they have already undertaken with the NHS, and the (few) reference sites this has generated.

Cerner and iSoft are the chosen CRS providers to London and the north, Midlands and east regions of England respectively, although they also sell to trusts outside these areas.

Emis is in a slightly different position, but also has a very strong NHS presence: it is best known for supplying the majority of GP surgeries, and is aiming to add larger NHS organisations to its customer list.

US-based Cerner has been working with the NHS for more than two decades and its flagship EHR system, Cerner Millennium, has so far been installed across 16 trusts and more than 70 hospitals since being launched in 2004, as the preferred NPfIT software for London. It also supplied the software for NPfIT's Choose and Book appointment scheduling system, which processed more than 15m patient bookings during 2009.

Cerner's existing customers include Kingston Hospital - which went live just inside the government's November 2009 target date - and Homerton Hospital in London, while other sites, such as Newham University Hospital trust and Wirral University Teaching Hospital foundation trust are extending their use of its technology. In June 2010, Wirral said it will start using the software in A&E. Newham is planning to extend its Millennium installation to deliver integrated patient care pathways for its citizens.

In partnership with its neighbour, Homerton University foundation trust, Newham was the first NHS site to implement Cerner Millennium around six years ago, and plans are now in place to implement fully-electronic prescriptions and electronic workflow for all aspects of the two trust's patient care process.

A version of Cerner Millennium modified by University of Pittsburgh Medical Centre has been bought by Newcastle upon Tyne hospitals foundation trust: the patient administration elements of the software suite went live across the trust in November 2009. The trust is in the process of extending Millennium's use to two primary care health centres which it runs in the city.

In June 2010, the Royal Free Hampstead trust announced the development of an auditable set of guidelines and actions for clinicians within its Cerner Millennium electronic patient record system.

Developed in conjunction with the BMJ Evidence Centre, the gastro-intestinal pilot has been well received and is expected to be offered to other Cerner sites in the UK. Under the pilot, clinical professionals can interface with guidelines on their local Cerner Millennium system and access data on the BMJ website for decision support, ordering tests from a single screen interface. Later in 2011, the trust will extend the pilot to include electronic prescribing facilities.

The second major firm offering EHR systems to the NHS is Australian company iSoft Health, which is currently in the process of being bought by US IT firm CSC. They are a good fit: CSC has been installing iSoft's Lorenzo suite in trusts across the north, Midlands and east of England under NPfIT, for which it holds the local service provider contracts. iSoft has a total customer base of more than 13,000 health organisations in more than 40 countries.

The company being bought by CSC was formerly known as IBA, which bought UK-based iSoft and took the firm's name. This represented a new chapter for the organisation: four former executives of the old iSoft, none of whom now works for the company, appeared in court in January 2010 regarding financial irregularities dating from before the first purchase.

The firm had already been moving away from reliance on its NPfIT contract. In April 2009, iSoft secured a £2.5m deal with Heatherwood and Wexham Park Hospitals foundation trust for its i.Patient Manager patient administration system (Pas) technology, as well as a refresh of its i.Clinical Manager platform. What was notable about the deal was the fact that the trust negotiated directly with iSoft for a replacement PAS rather than waiting for this to be developed by the National Programme for IT.

According to Adrian Stevens, iSoft's managing director, this contract was one of the first major deals in the NHS southern cluster, and is being serviced by Fujitsu - which formerly acted as the local service provider to the whole area, before abandoning this role in the National Programme.

In July 2010, iSoft installed a new A&E system at Dartford and Gravesham trust's Darent Valley hospital, while in August, the firm released e-prescribing and medication administration software (EPMA) in the UK. However, the end of that month saw chief executive Gary Cohen stepping aside from his post to help assist the board "in the evaluation of strategic options for the company".

The IHR is a Welsh Assembly Government initiative that allows important patient information to be securely shared between GPs, emergency care and out of hours services - with the patient's consent. It gives an electronic view of key information held on the GP's practice computer system.

In March 2011, iSoft landed a deal with NHS trusts in Leeds and York for an electronic pathology request/test results service. The system will handle 3.2m tests a year across both trusts. Based on iSoft's Viaduct integration tool, the new service is a centrally-hosted Web application for connecting laboratory information systems.

Emis - Egton Medical Information Systems - has been central to implementing EHRs in the NHS, ever since it started operations in the 1980s when Dr Peter Sowerby and Dr David Stables wrote the software for their GP practice in Egton in North Yorkshire.

In September 2010, Emis said it had received full roll-out approval for Emis Web, its new centrally-hosted cross-organisational healthcare system, and has since started a controlled roll-out to existing GP users.

In Tower Hamlets, the firm says that 300 community staff are now using the system to access relevant data from the GP record and recording their consultations, leading to the trust making time and efficiency savings, as well as improving data capture and reporting.

In March 2011, the firm won a contract to deliver a shared care record system fir primary healthcare teams across Cheshire. The pan-Cheshire initiative will be a major implementation of the Emis Web cross-organisational healthcare system outside GP surgeries, with 933 Emis Web access points installed in acute trusts, mental health facilities, clinics and some community facilities.